Numerical Modeling of Rock Mechanics Tests in Layered Media Using a Finite / Discrete Element Approach

A numerical simulation based on a finite/discrete element approach is used to study the deformation and failure process of standard rock mechanics tests on Opalinus clay samples, when subjected to static loading conditions. The layered structure of the Opalinus clay is considered and the resultant anisotropic behaviour is modelled. Rock heterogeneity is also taken into account, with the main purpose to visualize micro-cracks creation, coalescence and eventually propagation of a single macro-failure plane. Anisotropy is introduced in the model by mesoscopic bedding planes. Uniaxial compression tests have been simulated on samples having a layered structure oriented parallel, perpendicular and inclined at 45° with respect to the axial loading. The results obtained are analyzed in terms of the predicted “global mechanical response” which is compared to that available from experimental tests on Opalinus clay samples (Konietzky et al., 2003). FEM/DEM modeling has been used to simulate the genesis and propagation of fractures, the consequence of rock degradation and its change in behaviour from continuum to discontinuum.